Bearings, bearing apparatus, and systems including the same

ABSTRACT

A bearing ring for use in bearing apparatuses is disclosed. Such a bearing ring may comprise a body having a first array and a second array of bearing elements mounted to the body. The body may have an annular shape and the first array and the second array may be a concentric elliptical shapes, including circles. The body may comprise a plurality of bearing element pockets into which the bearing elements are disposed. In one aspect of the instant disclosure, the material of the bearing elements comprises polycrystalline diamond. A bearing apparatus comprising a first bearing ring and a second bearing ring is also disclosed. A drilling system for use in drilling subterranean formations employing the bearing apparatus is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/356,379, filed 20 Jan. 2009, now U.S. Pat. No. 8,480,304, registeredon 9 Jul. 2013, the disclosure of which is incorporated, in itsentirety, by this reference.

BACKGROUND

Conventional bearing apparatus, such as thrust bearings and radialbearings, typically include one or more annular members or bearingrings, such as a rotor and a stator, and a plurality of bearing elementsdisposed thereon. The bearing elements may be disposed in a singlecircular array of pockets in each of the annular members. The array ofpockets in the annular members may be concentric with the inner andouter edges of the annular member. In operation, two annular members maybe aligned with their respective bearing elements facing each other,such that the bearing elements contact one another while one or both ofthe annular members rotate.

While conventional bearings using superhard material for the bearingelements are capable of sustaining very high loads and speeds in avariety of operating conditions, the bearings are often damaged by heatgenerated by the friction between bearing elements during operation. Ifthe bearings are not designed to remove generated frictional heat,elevated bearing temperatures may result in bearing failure. Forexample, when the temperature of a bearing element rises above a certainthreshold temperature, the bearing element may begin to degrade.

In down-hole oil and gas drilling applications, this problem has beenaddressed through the use of cooling fluid. Usually in the form ofdrilling mud, the relatively cool fluid flows around the bearingelements to cool the bearing elements. Generated frictional heat istransferred from the bearing elements to the cooling fluid by convectiveheat transfer. The cooling fluid carrying the heat may then becirculated away from the bearing elements. However, because the coolingfluid flows around only the surfaces of the bearing elements, a thermalgradient is created within the bearing elements. That is to say, thecenter of the bearing elements remain hot while the outer surfaces ofthe elements are cooled by the cooling fluid. The heat at the center ofthe bearing elements may still result in bearing failure, and thereforethe use of cooling fluid alone has not fully addressed the problem offrictional heat generated by bearing elements.

One possible solution that has been previously postulated is to decreasethe size of bearing elements. By reducing the distance from the hot,central portion of the bearing element to the cool, outer portions ofthe bearing element, the maximum bearing element temperature may bereduced. However, reducing the bearing element size also reduces thetotal bearing element-to-bearing element contact area of the bearing,thus increasing the pressure on the bearing elements for the same axialload.

Thus, a need exists for an improved bearing capable of reducing oreliminating the effects of frictional heat without significantlyincreasing the pressure on the bearing elements.

SUMMARY

The instant disclosure relates generally to bearing rings, bearingapparatus, and drilling systems including bearing apparatus. In oneembodiment, the instant disclosure relates to bearing rings, bearingapparatus, and drilling systems including bearing elements comprisingsuperhard material, such as polycrystalline diamond (PCD).

One aspect of the instant disclosure relates to a bearing ring. Thebearing ring includes a body and a plurality of bearing elements. Thebody includes a first face and a second face opposing the first face.The plurality of bearing elements includes a first array of bearingelements and a second array of bearing elements. The first array ofbearing elements is mounted to the body and has an elliptical shape. Thesecond array of bearing elements is mounted to the body and has anelliptical shape. A size of at least one of the plurality of bearingelements may be different than a size of at least another of theplurality of bearing elements. A shape of at least one of the pluralityof bearing elements may be different than a shape of at least another ofthe plurality of bearing elements. The elliptical shapes of the firstarray and the second array may be generally circular and generallyconcentric. In one embodiment, the elliptical shapes of the first arrayand the second array are circular.

Each of the bearing elements may be disposed in a bearing element pocketdefined in the body. Each bearing element of the first array and eachbearing element of the second array may have a generally cylindricalshape, wherein each bearing element pocket has a generally cylindricalshape with a diameter that exceeds a diameter of each bearing elementdisposed therein. The bearing element pockets within the first array maybe circumferentially evenly spaced apart from one another and thebearing element pockets within the second array may be circumferentiallyevenly spaced apart from one another. Each bearing element may include atop end that extends out of the bearing element pocket into which it isdisposed, wherein the top end is beveled. Each bearing element mayinclude at least one of: polycrystalline diamond; tungsten carbide;silicon carbide; and cubic boron nitride. Further, each bearing elementmay include polycrystalline diamond compact.

Another aspect of the present disclosure relates to a bearing apparatus.The bearing apparatus includes a first bearing ring and a second bearingring. Each of the first and second bearing rings includes a body, afirst array of bearing elements, and a second array of bearing elements.The body includes a first face and a second face opposing the firstface. The first array of bearing elements is mounted to the body and hasan elliptical shape. The second array of bearing elements is mounted tothe body and has an elliptical shape. A size of at least one bearingelement within the first array of bearing elements of the first bearingring is different than a size of at least one bearing element within thesecond array of bearing elements of the first bearing ring. In someembodiments, a size of at least one bearing element within the firstarray of bearing elements of the second bearing ring is different than asize of at least one bearing element within the second array of bearingelements of the second bearing ring. Each bearing element may include atleast one of: polycrystalline diamond; tungsten carbide; siliconcarbide; and cubic boron nitride. The first bearing ring may comprise arotor and the second bearing ring may comprise a stator.

Another aspect of the present disclosure relates to a drilling systemfor use in drilling subterranean formations. The drilling system mayinclude a motor configured to apply a torque to a rotary drill bit andbeing operably coupled to a bearing apparatus. The bearing apparatus mayinclude at least one bearing ring having a body, a first array ofbearing elements, and a second array of bearing elements. The bodyincludes a first face and a second face opposing the first face. Thefirst array of bearing elements is mounted to the body and has anelliptical shape. The second array of bearing elements is mounted to thebody and has an elliptical shape. A size of at least one bearing elementwithin the first array may be different than a size of at least anotherbearing element within the second array. The bearing apparatus mayinclude a thrust bearing or a radial bearing.

A further aspect of the present disclosure relates to a bearing ring.The bearing ring includes a body and a plurality of bearing elements.The body includes a first face and a second face opposing the firstface. The plurality of bearing elements includes a first array ofbearing elements and a second array of bearing elements. The first arrayof bearing elements is mounted to the body and has an elliptical shape.The second array of bearing elements is mounted to the body and has anelliptical shape. A shape of at least one of the plurality of bearingelements may be different than a shape of at least another of theplurality of bearing elements. The elliptical shapes of the first arraymay be generally circular and generally concentric. Each of the bearingelements may be disposed in a bearing element pocket defined in thebody. The bearing element pockets within the first array may becircumferentially evenly spaced apart from one another and bearingelement pockets within the second array may be circumferentially evenlyspaced apart from one another.

Features from any of the above mentioned embodiments may be used incombination with one another, without limitation. In addition, otherfeatures and advantages of the instant disclosure will become apparentto those of ordinary skill in the art through consideration of theensuing description, the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate a number of exemplary embodimentsand are a part of the specification. Together with the followingdescription, these drawings demonstrate and explain various principlesof the instant disclosure.

FIG. 1 shows a perspective view of a bearing ring according to oneembodiment of the instant disclosure.

FIG. 2A shows a perspective view of a bearing element according to oneembodiment.

FIG. 2B shows a perspective view of a bearing element according to anadditional embodiment.

FIG. 2C shows a perspective view of a bearing element according to anadditional embodiment.

FIG. 3 shows a top elevational view of a bearing ring according to oneaspect of the instant disclosure.

FIG. 4 shows a top elevational view of a bearing ring according to oneaspect of the instant disclosure.

FIG. 5 shows a top elevational view of a bearing ring according to oneaspect of the instant disclosure.

FIG. 6 shows a top elevational view of a bearing ring according oneaspect of the instant disclosure.

FIG. 7 shows a side cross-sectional view of a bearing ring according tothe instant disclosure.

FIG. 8 shows a side cross-sectional view of a bearing ring according tothe instant disclosure.

FIG. 9 shows a perspective view of a bearing apparatus according to theinstant disclosure including a first bearing ring and a second bearingring.

FIG. 10 shows a perspective view of a subterranean drilling systemincluding a bearing apparatus according to the instant disclosure.

Throughout the drawings, identical reference characters and descriptionsindicate similar, but not necessarily identical, elements. While theexemplary embodiments described herein are susceptible to variousmodifications and alternative forms, specific embodiments have beenshown by way of example in the drawings and will be described in detailherein. However, the exemplary embodiments described herein are notintended to be limited to the particular forms disclosed. Rather, theinstant disclosure covers all modifications, equivalents, andalternatives falling within the scope of the appended claims.

DETAILED DESCRIPTION

The instant disclosure relates generally to bearing rings, bearingapparatus, and drilling systems having bearing elements mounted thereon.As used herein, the term “bearing ring” means a bearing rotor, a bearingstator, and/or any other bearing ring suitable for use in a thrustbearing, a radial bearing, and/or any other suitable bearing apparatus.In one embodiment, a bearing ring may include bearing elements mountedto the bearing ring wherein the bearing elements are arranged in a firstarray and a second array of bearing elements. More particularly, thebearing elements may be arranged on the bearing ring in a first arrayand a second array, which are each elliptical and alignedconcentrically. Such a configuration may provide a bearing apparatushaving relatively small bearing elements, but having the same bearingelement-to-bearing element contact area as a bearing apparatus having asingle array of larger bearing elements.

One aspect of the instant disclosure relates generally to bearing ringsincluding a body and a plurality of bearing elements mounted thereto.The plurality of bearing elements may be arranged in a first array and asecond array of bearing elements. Further, the first array and thesecond array of bearing elements may each have a generally ellipticalshape. Such a configuration may allow for the use of relatively smallbearing elements, which may be easier to cool by way of, for example,cooling fluid, than larger bearing elements due to the shorter distancebetween the outside surfaces of the bearing elements contacted by thecooling fluid and the center of the bearing element. At the same time,the bearing element-to-bearing element contact area may not be reducedrelative to a conventional bearing ring having a single array of largerbearing elements, and therefore the pressure on each bearing element maynot be increased.

In one embodiment, a bearing ring may include a plurality of bearingelements mounted thereto, wherein the bearing elements are arranged in afirst array and a second array. FIG. 1 shows a perspective view of abearing ring 10 according to one embodiment of the instant disclosure.Bearing ring 10 comprises a body 12 having a first face 14, a secondface 16, and a plurality of bearing elements 18 mounted thereto.

As shown in FIG. 1, body 12 may have an annular shape. However, theshape of body 12 is not limited and may include other shapes, such as acylinder or a cube. The material of body 12 is also not limited and mayinclude any suitable material for use in a bearing ring, such as a metalalloy. The size (e.g., inner diameter, outer diameter, thickness, etc.)of the body is not limited and may be scaled up or down for a variety ofuses and applications.

A plurality of bearing elements 18 arranged in a first array and asecond array may be mounted on first face 14 of body 12. Such mountingmay take place via any suitable means for securing bearing elements 18to body 12. For example, bearing elements 18 may be soldered to firstface 14 of body 12, bearing elements 18 may be adhered to first face 14of body 12 using a suitable braze material, bearing elements 18 may bepress fit into body 12, or bearing elements 18 may be affixed to firstface 14 of body 12 using a mechanical fastener (e.g., a screw) orsecured in any other suitable manner.

The material of bearing elements 18 is not limited and may represent anysuitable bearing element material. In one aspect of the instantdisclosure, bearing elements 18 may comprise a material selected fromthe group comprising polycrystalline diamond (PCD), tungsten carbide,silicon carbide, cubic boron nitride, and composites thereof. In anotheraspect of the instant disclosure, bearing elements 18 may includecontact surfaces comprising PCD.

The cross-sectional shape of bearing elements 18 is also not limited.For example, bearing elements 18 may be in the shape of a cylinder(including a regular cylinder, an elliptic cylinder, etc.), a cube, acuboid, or a polyhedron. FIGS. 2A, 2B, and 2C illustrate severaldifferent bearing elements 18 having various shapes. In FIG. 2A, bearingelement 18 is in the shape of a cylinder. In FIG. 2B, bearing element 18is in the shape of a cuboid. In FIG. 2C, bearing element 18 is in theshape of a polyhedron having an octagonal horizontal cross-section. Asillustrated in each of FIGS. 2A, 2B, and 2C, an end 19 of bearingelements 18 may comprise a flat portion 19 a and a beveled portion 19 b.End 19 of bearing element 18 may be the end of bearing element 18 thatextends away from body 12 of bearing ring 10 and which comes intocontact with bearing elements of another bearing ring.

As further illustrated in FIGS. 2A-2C, bearing element 18 mayadditionally comprise a substrate 23. A superhard material (e.g.,polycrystalline diamond, cubic boron nitride, silicon carbide, or anyother suitable superhard material, as described above) may be bonded tosubstrate 23. A superhard material bonded to substrate 23 may provide abearing surface (e.g., end 19 of bearing element 18) that is relativelywear resistant. In at least one embodiment, substrate 23 may comprise acarbide material, such as cobalt sintered tungsten carbide.Additionally, bearing element 18 may include a catalyst (e.g., cobalt,nickel, iron, or any other suitable catalyst) to facilitate formation ofpolycrystalline diamond on substrate 23. Optionally, at least a portionof a catalyst within bearing element 18 may at least partially beremoved using any suitable method, such as, for example, by acidleaching.

As with the size of body 12, the size of bearing elements 18 is notlimited and may be selected depending on the application of bearing ring10. Furthermore, as described in greater detail below, different bearingelements 18 mounted on a body 12 of a bearing ring 10 may be of varioussizes. For example, at least some of bearing elements 12 may be the samesize or may be different sizes. As also noted above, the plurality ofbearing elements 18 mounted on body 12 of bearing ring 10 may bearranged in a first array and a second array. The shape of the arrays ofbearing elements 18 may be generally elliptical. As used herein, thephrase “elliptical” means any type of ellipse, circle, oval, elongatedoval, or a substantially similar shape. The generally elliptical shapedfirst array and second array of bearing elements 18 may beconcentrically arranged on body 12 of bearing ring 10 or may be orientedabout different center points. In the example shown in FIG. 1, the firstarray and the second array of bearing elements 18 are substantiallyconcentric circles.

Because a first array and a second array of bearing elements 18 may beutilized, bearing elements 18 may be smaller relative to bearingelements used in a conventional, single-array bearing apparatus. Thesmaller bearing elements may be easier to cool via cooling fluid due tothe short distance between the outer edges of the bearing elements thatare most concurrently contacted by the cooling fluid and the center ofthe bearing elements. Optionally, the same or a similar bearingelement-to-bearing element contact area may be maintained as compared toa conventional single-array bearing apparatus due to the first array andthe second array of bearing elements, such that pressure exerted on eachbearing element may not be increased.

FIGS. 3-6 illustrate various configurations of arrays of bearingelements mounted on a body of a bearing ring contemplated in the instantdisclosure. In FIGS. 3-6, bearing ring 10 includes two arrays of bearingelements 18 arranged in a series of substantially concentric circles. InFIG. 3, bearing ring 10 includes two arrays of generally cylindricallyshaped bearing elements 18 wherein the diameter of each of bearingelements 18 is approximately the same. FIGS. 3-5 illustrate that thesize of bearing elements 18 mounted on bearing ring 10 may be the samefrom the first array to the second array or may vary from the firstarray to the second array. In FIG. 4, bearing ring 10 includes twoarrays of generally cylindrically shaped bearing elements 18 wherein thediameter of each bearing element 18 within the same array isapproximately the same, but wherein the diameter of bearing elements 18within an array decreases from the radially outermost array to theradially innermost array. In FIG. 5, bearing ring 10 includes two arraysof cylindrically shaped bearing elements 18 wherein the diameter of eachbearing element 18 within the same array is approximately the same, butwherein the diameter of bearing elements 18 within an array increasesfrom the radially outermost array to the radially innermost array. Ineach of FIGS. 3-5, bearing elements 18 within an array may be evenlycircumferentially spaced apart from each other.

In other arrangements, the size of each bearing element within an arraymay vary. Furthermore, while FIGS. 3-5 each illustrate arrays of bearingelements all having approximately the same shape within a given array,the shape of the bearing elements may vary within an array or betweenarrays. Similarly, while FIGS. 3-5 each illustrate arrays of bearingelements all having approximately the same contact area (i.e., the areaof the end of bearing elements extending out of bearing elementpockets), the contact area of the bearing elements may vary within anarray or between arrays.

For example, as illustrated in FIG. 6, the size of bearing elementsmounted on bearing ring 10 may vary within an array. In at least oneembodiment, as shown in FIG. 6, bearing ring 10 may include two arraysof generally cylindrically shaped bearing elements, wherein the diameterof bearing elements 18 a and bearing elements 18 b may vary within anarray. For example, bearing elements 18 a may have a larger diameterthan bearing elements 18 b in a single array. Additionally, bearingelements 18 a may alternate with bearing elements 18 b within an array.Bearing elements 18 a and bearing elements 18 b may also be evenlycircumferentially spaced apart from each other in an array.

In at least one embodiment, bearing elements 18 may be in bearingelement pockets 20 located in body 12, as shown in FIGS. 7 and 8. FIG. 7is a side cross-sectional view of bearing ring 10 shown in FIG. 1, takenalong line 8-8 with bearing elements 18 removed, and illustrates bearingelement pockets 20 in greater detail. As can be seen, bearing elementpockets 20 may extend into body 12 from first face 14. As shown in FIG.7, bearing element pockets 20 may not extend from first face 14 tosecond face 16 of body 12. In other embodiments of bearing ring 10,bearing element pockets 20 may extend through body 12 of bearing ring10.

FIG. 8 is a side cross-sectional view of bearing ring 10 shown in FIG.1, taken along line 8-8. As shown in FIG. 8, each of bearing elements 18may be disposed in an associated bearing element pocket 20 located inbody 12 of bearing ring 10. In one embodiment, the shape of bearingelement pocket 20 may be similar to the shape of bearing element 18. Forexample, when using a cylindrically shaped bearing element, bearingelement pocket 20 may have a generally cylindrical shape.

In one embodiment, each of bearing elements 18 may be disposed withinits respective bearing element pocket 20 and then secured within itsrespective bearing element pocket 20. The method for securing bearingelement 18 in bearing element pocket 20 is not limited and may include,for example, brazing (i.e., high temperature soldering), soldering,mechanical mechanisms such as screws, and interference (i.e., selectingthe size of the bearing element pocket to the size of the bearingelement such that the bearing element fits tightly in the bearingelement pocket and cannot be easily removed from the bearing elementpocket). A manner for securing bearing element 18 in bearing elementpocket 20 by interference is illustrated in FIG. 8. As illustrated inthis figure, the outer diameter of cylindrically shaped bearing element18 may exceed the diameter of cylindrically shaped bearing elementpocket 20 such that bearing element 18 fits tightly in bearing elementpocket 20. Such a configuration may limit or prevent bearing element 18from rotating within bearing element pocket 20 after having been securedin bearing element pocket 20.

In one aspect illustrated in FIG. 8, the height of bearing elements 18may be greater than the depth of bearing element pocket 20 into whicheach bearing element 18 is positioned. In this manner, end 19 of bearingelement 18 may protrude above first face 14 of body 12. In an alternateaspect where the height of bearing element 18 is not greater than thedepth of bearing element pocket 20, bearing element 18 may still beoriented in bearing element pocket 20 such that end 19 protrudes abovefirst face 14 of body 12. In one aspect of the instant disclosure, atleast a portion of end 19 of bearing element 18 protruding out ofbearing element pocket 20 may be substantially parallel to first surface14 of body 12. In another embodiment, each bearing element 18 mounted tobody 12 of bearing ring 10 may protrude out of body 12 to substantiallythe same distance away from first surface 14 such that ends 19 of eachbearing element 18 are substantially coplanar.

From the foregoing description, it may be appreciated that at least onebearing ring according to any of the embodiments described above may beused to form a bearing apparatus. For example, FIG. 9 shows aperspective view of a thrust bearing apparatus 100 including a firstbearing ring 10 a and a second bearing ring 10 b. During use, firstbearing ring 10 a and second bearing ring 10 b may be aligned with oneanother and ends 19 of bearing elements 18 mounted to bearing ring 10 amay be in contact with ends 19 of bearing elements 18 mounted to bearingring 10 b. First bearing ring 10 a and second bearing ring 10 b may alsobe affixed to a system to provide a thrust bearing structure. It shouldalso be appreciated that, in operation, first bearing ring 10 a mayrotate while second bearing ring 10 b may remain stationary, or viceversa. In one embodiment, bearing rings 10 a and 10 b may besubstantially identical (e.g., both bearing rings may have the samenumber of arrays, the same number of bearing elements within each array,bearing elements having the same shape and size, etc.). In anotherembodiment, bearing rings 10 a and 10 b are not identical (e.g., thefirst bearing ring and the second bearing ring may have differentnumbers of bearing elements, different sizes of bearing elements, etc.).

Thrust bearing apparatus 100 disclosed above may also be incorporatedinto a mechanical system. For example, FIG. 10 shows a perspective viewof a subterranean drilling system 110 incorporating thrust bearingapparatus 100. In particular, as known in the art, a rotary drill bit130 may be rotated by downhole drilling motor assembly 112. Downholedrilling motor assembly 112 may be located at the end of a series ofpipe sections comprising a drill string. The housing 114 of downholedrilling motor assembly 112 remains stationary as rotary drill bit 130rotates.

In further detail, output shaft 120 of downhole drilling motor assembly112 may be coupled to rotary drill bit 130 and drilling fluid (i.e.,drilling mud) may cause torque to be applied to output shaft 120 androtary drill bit 130. Rotary drill bit 130 is shown as a so-calledroller cone type bit including roller cones, but may be a fixed cutter(e.g., a drill bit including a polycrystalline diamond cutting elementsor compacts) or any other rotary drill bit or drilling tool (e.g., areamer, impregnated diamond drill bit, core bit, etc.) as known in theart, without limitation. As shown in FIG. 10, thrust bearing apparatus100 comprising first bearing ring 10 a and second bearing ring 10 b maybe operably assembled to downhole drilling assembly 112, as known in theart.

The preceding description has been provided to enable others skilled inthe art to best utilize various aspects of the exemplary embodimentsdisclosed herein. This exemplary description is not intended to beexhaustive or to be limited to any precise form disclosed. Manymodifications and variations are possible without departing from thespirit and scope of the instant disclosure. The embodiments disclosedherein should be considered in all respects illustrative and notrestrictive. Reference should be made to the appended claims and theirequivalents in determining the scope of the instant disclosure.

For example, although the bearing rings described above have beendiscussed in the context of down-hole drilling tools, it should beunderstood that such bearing rings are not limited to such use and couldbe used within a bearing apparatus or system for varied applications, ifdesired, without limitation. Thus, such apparatus and systems are notlimited to use with down-hole drilling tools and may be used withvarious other mechanical systems, without limitation.

Unless otherwise noted, the terms “a” or “an,” as used in thespecification and claims, are to be construed as meaning “at least oneof.” In addition, for ease of use, the words “including” and “having,”as used in the specification and claims, are interchangeable with andhave the same meaning as the word “comprising.”

What is claimed is:
 1. A bearing apparatus comprising: a first bearingring comprising: a body; a first plurality of bearing elements mountedto the body along a first radius; a second plurality of bearing elementsmounted to the body along a second radius, each of the second pluralityof bearing elements being larger than each of the first plurality ofbearing elements, wherein a quantity of the second plurality of bearingelements is different than a quantity of the first plurality of bearingelements; a second bearing ring comprising: a body; a first plurality ofbearing elements mounted to the body along a first radius; a secondplurality of bearing elements mounted to the body along a second radius;wherein the first bearing ring and the second bearing ring arepositioned adjacent each other such that the first plurality of bearingelements of the first bearing ring are aligned with the first pluralityof bearing elements of the second bearing ring and the second pluralityof bearing elements of the first bearing ring are aligned with thesecond plurality of bearing elements of the second bearing ring.
 2. Thebearing apparatus of claim 1, wherein each of the first plurality ofbearing elements of the first bearing ring and each of the secondplurality of bearing elements of the first bearing ring is disposed in abearing element pocket defined in the body of the first bearing ring. 3.The bearing apparatus of claim 2, wherein each of the first plurality ofbearing elements of the second bearing ring and each of the secondplurality of bearing elements of the second bearing ring is disposed ina bearing element pocket defined in the body of the second bearing ring.4. The bearing apparatus of claim 2, wherein each of the first pluralityof bearing elements of the first bearing ring is substantially equallycircumferentially spaced and wherein each of the second plurality ofbearing elements of the first bearing ring is substantially equallycircumferentially spaced.
 5. The bearing apparatus of claim 4, whereineach of the first plurality of bearing elements of the second bearingring is substantially equally circumferentially spaced and wherein eachof the second plurality of bearing elements of the second bearing ringis substantially equally circumferentially spaced.
 6. The bearingapparatus of claim 2, wherein the first radius of the first bearing ringis larger than the second radius of the first bearing ring.
 7. Thebearing apparatus of claim 6, wherein the first radius of the secondbearing ring is larger than the second radius of the second bearingring.
 8. The bearing apparatus of claim 1, wherein each bearing elementof the first and second pluralities of bearing elements of the firstbearing ring exhibits a substantially cylindrical geometry.
 9. Thebearing apparatus of claim 1, wherein each bearing element of the firstand second pluralities of bearing elements of the first bearing ringcomprises at least one of: polycrystalline diamond; tungsten carbide;silicon carbide; and cubic boron nitride.
 10. The bearing apparatus ofclaim 9, wherein each bearing element of the first and secondpluralities of bearing elements of the second bearing ring comprises atleast one of: polycrystalline diamond; tungsten carbide; siliconcarbide; and cubic boron nitride.
 11. The bearing apparatus of claim 9,wherein each bearing element of the first and second pluralities ofbearing elements of the first bearing ring comprises a top surface, aside surface and a bevel between the top surface and the side surface.12. The bearing apparatus of claim 1, wherein the first bearing ringcomprises a rotor and wherein the second bearing ring comprises astator.
 13. The bearing apparatus of claim 1, wherein, in the secondbearing ring, each of the second plurality of bearing elements arelarger than each of the first plurality of bearing elements and whereina quantity of the second plurality of bearing elements is different thana quantity of the first plurality of bearing elements.
 14. A drillingsystem for use in drilling subterranean formations, the drilling systemcomprising: a motor configured to apply a torque to a rotary drill bit,the motor operably coupled to a bearing apparatus; wherein the bearingapparatus comprises: a first bearing ring comprising: a body; a firstplurality of bearing elements mounted to the body along a first radius;a second plurality of bearing elements mounted to the body along asecond radius, each of the second plurality of bearing elements beinglarger than each of the first plurality of bearing elements, wherein aquantity of the second plurality of bearing elements is different than aquantity of the first plurality of bearing elements; a second bearingring comprising: a body; a first plurality of bearing elements mountedto the body along a first radius; a second plurality of bearing elementsmounted to the body along a second radius; wherein the first bearingring and the second bearing ring are positioned adjacent each other suchthat the first plurality of bearing elements of the first bearing ringare aligned with the first plurality of bearing elements of the secondbearing ring and the second plurality of bearing elements of the firstbearing ring are aligned with the second plurality of bearing elementsof the second bearing ring.
 15. The drilling system of claim 14, whereinthe bearing apparatus comprises a thrust bearing.
 16. The drillingsystem of claim 14, wherein the first bearing ring comprises a rotor andwherein the second bearing ring comprises a stator.
 17. The drillingsystem of claim 14, wherein each of the first plurality of bearingelements of the first bearing ring is substantially equallycircumferentially spaced and wherein each of the second plurality ofbearing elements of the first bearing ring is substantially equallycircumferentially spaced.
 18. The drilling system of claim 17, whereineach of the first plurality of bearing elements of the second bearingring is substantially equally circumferentially spaced and wherein eachof the second plurality of bearing elements of the second bearing ringis substantially equally circumferentially spaced.
 19. The drillingsystem of claim 14, wherein the first radius of the first bearing ringis larger than the second radius of the first bearing ring.
 20. Thedrilling system of claim 19, wherein the first radius of the secondbearing ring is larger than the second radius of the second bearingring.
 21. The drilling system of claim 14, wherein each bearing elementof the first and second pluralities of bearing elements of the firstbearing ring comprises at least one of: polycrystalline diamond;tungsten carbide; silicon carbide; and cubic boron nitride.
 22. Thedrilling system of claim 21, wherein each bearing element of the firstand second pluralities of bearing elements of the second bearing ringcomprises at least one of: polycrystalline diamond; tungsten carbide;silicon carbide; and cubic boron nitride.
 23. The bearing apparatus ofclaim 21, wherein each bearing element of the first and secondpluralities of bearing elements of the first bearing ring comprises atop surface, a side surface and a bevel between the top surface and theside surface.
 24. The bearing apparatus of claim 14, wherein, in thesecond bearing ring, each of the second plurality of bearing elementsare larger than each of the first plurality of bearing elements andwherein a quantity of the second plurality of bearing elements isdifferent than a quantity of the first plurality of bearing elements.